In the Kingdom of Bandiera, the royal prophet has announced the incoming resurrection of the Demon King, 500 years after the first King sealed it.

Four heroes were thus chosen and sent to the location of the Demon's prison. Meanwhile, Charlie Barett, a modest gate keeper, is stuck at the Royal City with a job he hates, spending his days complaining to his captain and his co-workers; one of which is the noticeably generic-looking Jimmy Monbarn.

Demons, they are born from stagnation, fear, hatred, and sorrow. Attracted by negative emotions of humans. In this world there are people who were able to fight against them, they possess the skill of a secret art. Transforming their soul into a blade, they are called Onmyouji.